Methods Of Preserving Starch In Pulp And Controlling Calcium Precipitation And/Or Scaling

ABSTRACT

Methods to preserve starch present in pulp are provided and also methods to control calcium precipitation and/or scaling in digesters or BOD systems. The methods can be performed as part of a papermaking process. Process water containing pulp can be treated with a chloramine. Process water containing pulp with native starch can receive a double treatment with at least one biocide, such as chloramine, and at least one oxidant, such as sodium hypochlorite. The treatment can be performed in any suitable manner. The treatment can be performed at one or more stages or locations in a papermaking system. A target residual chloramine value or range can be achieved by the treatment. Packaging sheets/boards and other paper products manufactured using the methods provided exhibit superior strength and other desirable characteristics.

This application claims the benefit under 35 U.S.C. §119(e) of priorU.S. Provisional Patent Application No. 61/655,678, filed Jun. 5, 2012,which is incorporated in its entirety by reference herein.

BACKGROUND OF THE INVENTION

The present invention relates to papermaking and/or the use of recycledpaper/paperboard, and also relates to preserving the starch content ofpulp during paper and packaging manufacturing, and further relates tocontrolling calcium precipitation and/or scaling in the treatment ofwaste water effluents.

Recycling is a major factor in the modern green economy and isparticularly significant in the paper industry's goal to become moreefficient and environmentally sustainable. Use of recycled pulp in paperand packaging manufacturing, however, presents several obstacles toachieving high-quality product. Recycled pulp, for example, derived fromold corrugated cardboard, writing/printing grades sized or coated withstarch, contain starch, usually at high levels, and are beneficial tomaking recycled paper/paperboard. The grades of paper/cardboard to berecycled also have beneficial levels of CaCO₃. Unfortunately, thisstarch content can become substantially degraded during manufacturing ascan supplemental starch added during the manufacturing. Less starch inthe resulting product means a loss of or lower mechanical properties inthe paper/paperboard product made from the pulp. Further, the calciumfound in pulp, such as pulp from recycled sources, can cause calciumprecipitation, scaling or fouling in the post treatment of process waterthat occurs after pulp removal.

More specifically, in the past, numerous papermaking plants (especiallythose using recycled paper) have experienced numerous problems that mayhave been related to bacterial problems. However, when the standardapproach to combating bacteria was attempted, no success was achieved.Biocides typically used in the papermaking industry and/or typicalbiocide treatments did not solve the following problems that were beingseen in many machines making packaging papers. Those in the industrycould not understand what was the exact problem and could not determinea solution to the problem. The present inventor however, determined thata particular microbial activity initiated the following sequence:

-   -   Microorganisms release amylases into the papermaking system.    -   These extracellular enzymes degrade starch into glucose        oligomers (e.g., maltose) and glucose (the starch for instance,        comes from waste paper, broke and/or wet end additive starch).    -   The oligomers and monomers are taken up by bacteria and are        fermented producing volatile fatty acid (VFAs).    -   VFAs decrease the process pH (from 7 or higher to 6.5-6 or        lower).    -   The fermentation process is accompanied by an increase in        conductivity and decrease in redox potential.    -   The pH in localized areas around fermenting bacteria can be as        low as 1 to 4.    -   Low pH dissolves calcium carbonate filler (for instance as        present in waste paper) into soluble calcium Ca²⁺ (and CO₂).        At this point, the problems only get worse: (1) increased growth        of fermenting bacteria results in increased production of        extracellular amylases; (2) any starch added for strength in the        wet end (between mixing chest and head box) is degraded; (3) the        glucose oligomers encourage even more growth of microorganisms        and so increase slime and/or other bacteria problems; (4) VFAs        are a cause of serious odor problems in the paper as well as in        the production environment and/or in the surroundings,        potentially including habitation areas; (5) when calcium        carbonate is dissolved and stabilized by VFAs, filler (e.g.,        from waste paper) is lost, essentially a loss of raw material;        and/or (6) dissolved calcium can cause deposit or scaling        problems.

In mills utilizing anaerobic digesters for waste water treatment,another related problem can develop, as follows:

-   -   VFAs react to stabilize dissolved calcium (as VFA-Ca salts) and        carry that calcium into the waste water treatment system.    -   With conversion of VFAs into CH₄ and CO₂ and a pH increase in        the anaerobic digester, calcium scale forms; if excessive scale        is formed this can shut down the waste treatment system, which        in turn could cause the shutdown of the mill for cleaning of the        anaerobic digester.

In mills utilizing aerobic digesters or ponds for waste water treatment,alone or in combination with anaerobic digesters, problems with CaCO₃fall-out can develop, as follows:

-   -   VFAs react to stabilize dissolved calcium (as VFA-Ca salts) and        carry that calcium into the waste water treatment system.    -   With (further) degradation of VFAs in the effluent and with        further pH increase during the effluent treatment, calcium        carbonate can precipitate resulting in scaling (aerobic        reactors) or excessive sludge formation (in aerobic ponds). This        can lead to increased downtime for maintenance and cleaning and        can cause significant cost for the disposal of CaCO₃-rich sludge        as chemical waste.

The present inventor was the first to understand the root of the problemand how to prevent and/or control this problem. The approach used by thepresent inventor, as described herein, is to reduce or prevent thebreakdown of starch by microbiological activity in the paper mill. Theroot causes of the problem are in summary:

-   -   The bacteria and the amylase enzymes produced by the bacteria in        the paper machines, because amylase enzymes are very efficient        in breaking down starch, for instance, to maltose and glucose.    -   The stimulation of fermentation metabolism of facultative        anaerobic bacteria by high glucose and sugar content in the        process water resulting in high levels of VFAs being produced        which are at the origin of the solubilisation of calcium filler        in the process.

Thus, the present inventor determined that the best way to solve thisproblem was to get ahead of the problem and stop the terrible chain ofevents that are detailed above.

SUMMARY OF THE PRESENT INVENTION

It is therefore a feature of the present invention to improve strengthin paper products (especially ones from recycled pulp or pulp fromrecycled sources) such as packaging sheets/boards, fluting, liner, testliner, single/multilayer and the like, by preserving the starch contentof pulp used to manufacture the same. The treatment of the presentinvention can be used on Foudrinier and on roundformer machines.

Another feature of the present invention is to increase the efficiencyof wet end additives in paper and packaging manufacturing. This forinstance can be achieved through reduction of Ca²⁺, pH increase, and/orlower conductivity.

A further feature of the present invention is to reduce odor-causingmaterials that can form during paper and packaging manufacturing.

Yet another feature of the present invention is the reduction of holesand microbiological-related breaks in paper and packaging being formedand in the completed product.

Another feature of the present invention is the preservation ofpre-existing and/or newly added, strength-imparting (native) starchand/or preexisting and/or newly formed starch-cellulose complexes inrecycled pulp and/or broke and/or other pulp source material fromamylase degradation to allow efficient recovery and transfer of thepre-existing and/or newly added starch and/or preexisting and/or newlyformed starch-cellulose complexes into a new sheet manufactured with therecycled pulp or broke.

Additional features and advantages of the present invention will be setforth in part in the description that follows, and in part will beapparent from the description, or may be learned by practice of thepresent invention. The objectives and other advantages of the presentinvention will be realized and attained by means of the elements andcombinations particularly pointed out in the description and appendedclaims.

To achieve these and other advantages, and in accordance with thepurposes of the present invention, as embodied and broadly describedherein, the present invention relates to a method to preserve starchpresent in pulp and in process waters. The method can be performed aspart of a papermaking process. Process water containing pulp can betreated with a chloramine(s). The treatment can be performed in anysuitable manner. The treatment can be continuous, substantiallycontinuous, intermittent, cyclic, batch, or any combination thereof.Preferably the treatment maintains an effective amount of chloramine inthe process water to achieve one or more benefits mentioned here andgenerally this effective amount is achieved by maintaining a residualamount of chloramine in the process water over a long continuous periodof time. The treatment can be performed at one or more stages orlocations in a papermaking system. For example, the treatment can beperformed in a vessel such as a head box, and/or at one or morelocations upstream and/or downstream of the headbox. A target residualchloramine value or range can be achieved by the treatment. For example,the process water can have a residual chloramine amount of from about0.3 ppm to about 15 ppm (or chlorine equivalents). The ppm level isexpressed as chlorine equivalents as is known and understood by thoseskilled in the art, and are not as actual chloramine ppm's in theprocess water. This residual amount can be determined, for instance, atthe headbox, or just prior or just after the headbox (as just oneexample of a measurement location). The starch can be present in thepulp in a desired amount. For example, the starch can be present in thepulp in an amount of at least about 0.001 wt % based on the total weightof dried pulp fiber, such as 0.1 wt % or higher, or 1 wt % or higher,based on the total weight of dried pulp fiber. The present inventionincludes the surprising and unexpected discovery that chloramine whenused in sufficient quantities and in a substantially continuous orcontinuous manner, can dramatically preserve starch content, such as,but not limited to cationic starch and/or native starch from size,coatings, sprays, and/or glues, that is present in the pulp, thusleading to packaging and paper products with enhanced propertiesincluding strength.

The present invention relates to a method for microorganism control andstarch protection in pulp in a papermaking process or other processwhich comprises a dual treatment of process water containing pulp withbiocide and oxidant. The biocide (e.g., chloramine and/or otherbiocides) can reduce or eliminate microorganisms capable of producingstarch-degrading enzymes, such as amylase (such as α-amylase) or otherstarch-degrading enzymes, in the process water. The oxidant (e.g.,sodium hypochlorite and/or other oxidants) can provide enzyme control toeliminate residual enzymatic activity of starch-degrading enzymes (suchas those produced by microorganisms) or other enzymes. With theindicated dual treatment, enzyme substrates (such as native starches orother enzyme substrates) can be protected from degradation by suchenzymes. The dual treatment method can reduce or eliminate counts ofbacteria and/or other microorganisms that are starch-degrading enzymeproducing and/or other microorganisms, in process water containing thepulp as compared to treatment of the process water containing the pulpwithout the biocide and oxidant. The dual treatment further can reduceor eliminate starch-degrading enzyme counts in the treated process wateras compared to treatment of the process water containing the pulpwithout the biocide and oxidant.

The present invention relates to a method to preserve pre-existing andnewly added (native) starch and pre-existing and newly formed (native)starch-cellulose complexes present in pulp in a papermaking processcomprising treating process water containing pulp comprising complexesor aggregates of cellulose and native starch, wherein the treatingcomprises separately adding chloramine and oxidant (e.g., sodiumhypochlorite) to the process water. The starch-degrading enzyme content(e.g., amylase content) in the treated process water is reduced comparedto a similar treatment of the process water without the oxidant. Themethod can be used to preserve pre-existing as well as newly formed(native) starch and starch-cellulose complexes in recycled pulp, broke,or both used in a papermaking process which comprises the indicateddouble treatment strategy. An oxidant, e.g., sodium hypochlorite(NaOCl), is used to reduce or eliminate starch-degrading enzyme (e.g.,amylase) from a process, such as a papermaking process, and chloramineis separately used from the oxidant in the process to reduce oreliminate microbiological infection and prevent or at least reducestarch-degrading enzyme (e.g., amylase) production in the process fromstarch-degrading enzyme producing microorganisms. (Native) starch andstarch-cellulose complexes in recycled paper or broke are preservedwhich can contribute to strength in new sheets manufactured with therecycled pulp or broke. Starch-degrading enzyme producingmicroorganisms, such as amylase-producing bacteria, can produce enzymesthat can degrade free starch if present in the process water, and alsostarch that is complexed with cellulose in aggregates that areintroduced into a papermaking process from recycled papers or broke andthe like and/or formed in-situ from new starch (native or cationic)added to the process which forms new bonds with fiber. The presentinvention includes the surprising and unexpected discovery that (native)starch present in recycled pulp or broke that is not mechanicallyremovable (e.g., by processes such as repulping, mixing, refining andother paper processes) is vulnerable to release by starch-degradingaction (e.g., amylolytic action), wherein the indicated double treatmentstrategy can reduce or prevent such starch-degrading action (e.g.,amylolytic action) to allow efficient recovery and transfer of thepre-existing (native) starch and starch-cellulose complexes into a newsheet manufactured with the recycled pulp or broke. The indicated doubletreatment strategy alternatively or additionally can reduce and/orprevent such starch-degrading action on newly added starch (native orcationic), which can be present in the process as free starch and/or incomplexed form wherein new bonds are created in-situ between this newstarch and fiber in the process. The indicated double treatment strategycan protect, at least partially or fully, such newly added starch and/ornewly formed starch-fiber complexes from amylolytic action.

The methods of the present invention also have the added benefits ofcontrolling the growth of microorganisms, reducing the production ofvolatile fatty acids (VFAs), preventing conductivity increases,preventing decreases in redox potential, lowering calcium dissolution,increasing pH, and/or minimizing precipitation on and/or scaling ofmachinery—especially in anaerobic digesters. The methods of the presentinvention can increase the efficiency of cationic wet end additives, forexample, retention polymers, starches, and/or dry strength resins.Improved strength allows for lower strength additive costs, reduction inbasis weight, and use of product in higher strength grade markets.

The methods of the present invention can result in maintaining orincreasing filler and/or ash content in the sheet product. For instance,solid calcium that would have been dissolved in conventional systems, isinstead retained in the sheet as a raw material. Lower calcium ionconcentrations (lower precipitated calcium levels) lead to increaseduptake of starch into sheets including binding of starch to fillerparticles. Reduction in chemistry usage is also realized in multiplecontexts including in the paper machine and subsequently in a biologicalwaste water plant. Increased machine output due to reduction in sizepress starch solids and the option to transition from size press to wetend starch addition are also made possible. Also, with the presentinvention, a drying energy reduction can be achieved by the eliminationof (1 or 2 sides of 2-sided) size press. Reduction in the amount ofsludge to be landfilled and reduction in effluent plant polymertreatment are further made possible by the methods of the presentinvention.

It is to be understood that both the foregoing general description andthe following detailed description are exemplary and explanatory onlyand are intended to provide a further explanation of the presentinvention, as claimed.

The accompanying drawings, which are incorporated in and constitute apart of this application, illustrate some of the features of the presentinvention and together with the description, serve to explain theprinciples of the present invention.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention may be more fully understood with reference to theaccompanying figures. The figures are intended to illustrate exemplaryfeatures of the present invention without limiting the scope of theinvention.

FIG. 1 is a process flow chart illustrating a method according to anexample of the present application.

FIG. 2 is a process flow chart illustrating a method according to anexample of the present application.

DETAILED DESCRIPTION OF THE PRESENT INVENTION

In accordance with the present invention, a method to preserve starchpresent in pulp is provided. The method can be performed as part of apapermaking process.

A key point in achieving effective control of the problems detailedabove is using the correct biocidal treatment, and this involves usingthe correct biocide, the correct dosage, the correct applicationpoint(s), maintaining the correct residual biocidal levels, and to keepdoing this over an extended period of time. It was determined that highlevels of one or more chloramines must be maintained to control theproblems detailed above. Essentially, the present inventor determinedthat a very aggressive and persistent treatment schedule is needed asdetailed herein.

In more detail, the method to preserve starch present in pulp can beincorporated into a papermaking process. For instance, the papermakingprocess can have a head box or roundformer machines, and the like. Thislocation(s) can be a treatment area, though this is optional. The methodinvolves treating process water containing the pulp or process waterused in the pulp preparation and paper production process with one ormore chloramines comprising monochloramine, such that the process waterhas a residual chloramine amount, such as in the amount of from 0.3 ppmto 15 ppm (chlorine equivalent) (as for instance measured at the headbox or other location where pulp is present). The starch can be presentin the pulp in an amount of at least 0.001 wt % based on weight of driedpulp fiber. Further details, options, and examples are provided below.

Process water containing pulp can be treated with one or morechloramines, for example monochloramine (MCA), dichloramine (DCA), or acombination thereof. A majority (by weight) of the chloramine can be MCA(such as at least 50.1%, at least 60%, at least 70%, at least 80%, atleast 90%, at least 95%, at least 99% or 100% by weight of thechloramine present). The treatment can be performed in any suitablemanner. The treatment can be continuous, substantially continuous,intermittent, cyclic, batch, or any combination thereof. The treatmentcan be performed at one or more stages or locations in a papermakingsystem. For example, the treatment can be performed in a vessel such asa head box, treating pulper, pulper fill water or dump chest, or anycombinations thereof. Generally, the treatment(s) occurs where the pulpis present with the process water and/or the process paper prior tobeing combined with pulp can be pre-treated with the chloramine asdescribed herein.

Methods of the present invention can comprise a method for microorganismcontrol and starch protection in pulp in a papermaking processcomprising a dual treatment of process water containing pulp withbiocide and oxidant. The microorganisms that are controlled can bebacteria, fungi, yeasts, archaebacteria, or other microorganisms thatcan produce starch-degrading enzymes, such as in process water in apapermaking process or other processes. The microorganisms that can becontrolled with the treatment can be predominantly bacteria, essentiallyentirely, or entirely bacteria. Infection control can be providedthrough the biocide (e.g., chloramine and/or other biocides) to reduceor eliminate the presence of microorganisms in the process water thatare capable of producing starch-degrading enzymes, such as amylase(e.g., α-amylase) or other enzymes, to reduce production of starchcomplex-degrading enzymes and the presence thereof in the process water.α-amylase (alpha amylase) is an endo-amylase that can quickly reducemolecular weight and also release starch from cellulose. β-amylase(beta-amylase) and γ-amylase (gamma-amylase) are terminal amylases whichrelease di/mono sugars. Without being limited to the scope of thisinvention, though β-amylase (beta-amylase) and γ-amylase typically maynot have a main role relating to starch stability in papermaking, theycan play a role in making the sugars ultimately available to bacteria,whether producing amylases or not. For purposes of the presentinvention, all or some or one of the amylase types α-amylase and/orβ-amylase and/or γ-amylase) can be controlled and/or prevented asdescribed herein. By controlling and/or preventing α-amylase alone orwith any other amylase type, the benefits of the present invention canbe achieved. When reference is made to “amylase” herein, it can includeone or more or all of the amylase types and preferably includes at leastα-amylase. The oxidant (e.g., sodium hypochlorite and/or other oxidants)can provide enzyme control to reduce or eliminate residual enzymaticactivity of starch-degrading enzymes (such as those produced bymicroorganisms) or other enzymes. With the indicated dual treatment,enzyme substrates (such as native starches and/or other enzymesubstrates) can be protected from degradation by such enzymes. Themicroorganism control, such as microbial infection control, provided bythe method can reduce or eliminate counts of bacteria and/or othermicroorganisms that are starch-degrading enzyme producing and/or othertypes of microorganisms, in process water containing the pulp ascompared to treatment of the process water containing the pulp withoutthe biocide and oxidant. The control of microorganisms that can bestarch-degrading enzyme producing by the method can be to belowdetectable levels or other values. The dual treatment further can reduceor eliminate starch-degrading enzyme counts in the treated process wateras compared to treatment of the process water containing the pulpwithout the biocide and oxidant. The control of starch-degrading enzymesby the method can be to below detectable levels or other values.

Methods of the present invention can comprise the use of the chloramineand at least one other active in a coordinated manner in the sameprocess. Chloramine and oxidant (e.g., sodium hypochlorite (NaOCl)) canbe used in a coordinated manner in the same process. Using these activesof chloramine and oxidant (e.g., sodium hypochlorite), a method topreserve pre-existing (native) starch and starch-cellulose complexes inrecycled pulp or broke from starch-degrading enzymatic action, such asamylase degradation, in a papermaking process or other process usingsuch recycled pulp or broke materials is provided. Native starch can bepresent in recycled pulp or broke from size, coatings, sprays, and/orglues. Rather than assuming that during pulping of recycled paper orbroke and subsequent steps in the paper production process that existingcomplexes or aggregates of cellulose and starch are completelydisrupted, it is a finding of the present invention that actually asubstantial quantity of starch remains in tight association withcellulose in such materials. In a study, after pulping in water(uninfected and free of amylase) and several washing steps with water,no more starch can be recovered from the fiber fraction. However, inthis study, when amylase is added to the water, a very significantamount of starch and starch degradation products are then stillreleased, indicating that some fraction of the starch is present intight association with the fiber that cannot be removed by meremechanical means (such as pulping, refining or washing), but which canbe released by specific amylase action. This discovery provides anexplanation of how starch protected from (enzymatic) amylase degradationcan contribute to strength. By preventing presence of amylase andamylase degradation of starch, not only is non-complexed or free starchprotected that can be present in the process (e.g., as released frompulped fibers, in recycled or broke), but pre-existing cellulose-starchcomplexes are also protected. The pre-existing cellulose-starchcomplexes can contain native starch that is not mechanically removed byprocesses such as repulping, mixing, refining and other paper processes,or at least not as easily or to the same extent as starch not containedin cellulose-starch complexes. Such cellulose-starch complexes can bevery efficiently retained in the new sheet to ensure the incorporationof a (substantial) fraction of the recycled starch into the new sheet.The indicated double treatment strategy alternatively or additionallycan reduce and/or prevent such starch-degrading action on newly addedstarch (native or cationic), such as newly added starch that is notremoved through pulpers or refiners, which can be present in the processas free starch and/or in complexed form wherein new bonds are createdin-situ between this new starch and fiber in the process. In this way,new starch-fiber complexes may be formed in-situ during the process. Theindicated double treatment strategy can protect such newly added starchand/or newly formed starch-fiber complexes from amylolytic action.

The existence of the cellulose-starch complexes in starch/calciumstabilization in industrial applications, with appropriate amylasecontrol by a method of the present invention, has been shown inexperimental tests.

With the indicated dual treatment of a method of the present invention,starch that returns with recycled fiber (e.g., fiber from oldpaper/paperboard, mixed office waste, coated fine paper, broke, and thelike) can be protected from enzymatic degradation. This protection canbe provided to many types of starch in such papers, such as for nativestarches derived from starch spraying, glues, coatings, size, and otherstarch sources. These starches typically have no active way of bindingto cellulose in the newly formed sheet, and they can benefit from theprotection of pre-existing starch-cellulose aggregates by preventingdissociation of such aggregates by undesired amylase degradation.Furthermore, eliminating amylase activity by a dual treatment of amethod of the present invention can protect high molecular weight starchmolecules that can impart better strength than low molecular weightmolecules. Cationic starches can remain attached to cellulose in theprocess of repulping and making a new sheet. These molecules can benefitfrom the elimination of amylase in the process as it can preserve theirhigh molecular weight against degradation to smaller less strengthimparting molecules. For recycled starch that is protected fromdegradation by a method of the present invention, and especially for thecellulose-starch complexes, the protection can be provided for at leastone of a) the recycled starch protected from amylase degradation whichretains a high average molecular weight, such as in the range of fromabout 10⁶ to about 10⁸, such as determined by size exclusionchromatography, 2) free high molecular weight starch, and/or 3)cellulose-high molecular weight starch aggregates. The weight of starchin cellulose-starch complexes protected from amylase degradation by amethod of the present invention can be on average higher than inaggregates not protected from degradation by the method.

These cellulose-starch complexes (aggregates) can contain filler, andpreventing degradation of starch can contribute to increasing fillerretention and ash increase in the new sheet. There may be pre-existingstarch-filler and/or starch-filler-cellulose complexes that remainintact after repulping. Keeping starch intact in these complexes canbenefit strength and filler retention. In a similar way thatstarch-cellulose complexes can be carried into a new sheet to therebytransfer the native starch into the new sheet (something it would notnormally do very efficiently by itself), filler complexes may be keptintact and transferred efficiently from recycled paper used as a pulpsource to a new sheet. This may explain at least in part how significantincreases in ash content in a new sheet can be obtained with apapermaking method of the present invention when calcium is preventedfrom solubilisation.

In more detail, the method to preserve pre-existing starch andcellulose-starch complexes in recycled pulp, broke, or both can comprisea double treatment strategy. Sodium hypochlorite (NaOCl) or otheroxidant can be used to specifically reduce or eliminate amylase from aprocess, such as a papermaking process, and chloramine can be separatelyused, from the sodium hypochlorite or other oxidant, in the process toreduce or eliminate microbiological infection and prevent amylaseproduction in the process. Chloramine reacts with the free chlorine ofNaOCl or free halogen of other halogen-releasing oxidant, resulting indestruction of both actives. To prevent mixing of these actives inprocess water, separate addition positions for these actives in aprocess, sequential additions of these actives from the same position ina process, or both, can be used for the additions of chloramine andNaOCl to prevent them from mixing in the process. NaOCl can be added insub-demand concentrations upstream of chloramine addition (or chloraminere-addition following an earlier chloramine addition and exhaustionthereof), wherein free chlorine will not move forward from its positionof addition, or other strategies can be used to keep the chemicals apartin the process waters. Minor amounts of the NaOCl and chloramine belowthe detection limit for free chlorine or mca in process waters of0.05-0.1 ppm as chlorine may be allowed to mix or inadvertently mix inthe process solution (e.g. 5 wt % or less). The amount of chloramineadded to the process solution can be an amount effective to reduce oreliminate microorganisms that can produce starch-degrading enzymes, andthe amount of NaOCl added to the process solution can be an amounteffective to provide amylase control to eliminate or at least reduceresidual activity of the enzyme.

As an option, a “sacrificial” oxidant (examples are hydrogen peroxide(H₂O₂) or sodium hypochlorite (NaOCl)) can additionally be used toeliminate reducing agents other than microbiological from the processwater. This sacrificial oxidant treatment can be used in combinationwith the chloramine treatment described herein. The sacrificial oxidant,if used in combination with the indicated method which provides the dualtreatment including control of microbial infection and starch-degradingenzymes, can be used in addition to the same or different kind ofoxidant used for the indicated dual treatment. The sacrificial oxidant,if used, can be added in the same production line as the chloramine, butnot necessarily at the same time. As indicated, chloramine tends toreact with the free chlorine of NaOCl or free halogen of otherhalogen-releasing oxidant, and preferably, these actives, when both areused in a process, are used separately.

As used herein, “preserve” or variants such as “preserves,”“preservation,” or “preserving,” refers to a reduction and/or preventionin the decomposition of starch or a component thereof, such as amyloseor amylopectin, in a composition that contains one or more starchdecomposing enzyme and starch. The amount of reduction can be measuredin relative terms by determining the starch level in a compositioncontaining a starch decomposing enzyme, starch, and chloramine, incomparison to the same composition without the presence of chloramine,for a similar monitoring period. The starch levels can be assayed byconventional means used for that purpose. Other monitoring tools can beused, such as size exclusion chromatography which in addition toquantity also describes quality of the starch by giving information onmolecular weight distribution in the starch and relative contribution ofdifferent molecular weights to the starch mix. The mechanism of theeffect on the activity and/or production of enzymes is not particularlylimited. The mechanism can at least partly reduce or prevent the effectsof the enzymes to catalyze decomposition of starch, and does not requireor exclude control of the microorganisms per se that produce theenzymes.

The pulp used in the present invention can be any suitable variety ofpulp or combination of pulps. The pulp can be derived from hardwood,softwood, or a combination thereof. The pulp can be virgin, recycled, ora combination thereof. The pulp can be obtained from one or more sourcessuch as broke, recycled packaging, old corrugated containers (OCC),mixed office waste (MOW), coated fine paper, baled mixed paper, sortedoffice paper, deinking grade newsprint, news blank, boxboard, boxboardwith polymer, waxed boxboard, boxboard with foil, baled corrugatedcardboard, waxed corrugated cardboard, beer carton waste, double linedkraft, bleached kraft, lightly printed bleached kraft, printed bleachedkraft, colored kraft, brown kraft, kraft multiwall bag waste, kraftmultiwall polybag waste, carrier stock, mixed envelope (new), whiteenvelope, plastic windowed white envelope, colored envelope, plasticwindowed colored envelope, kraft envelope, plastic windowed kraftenvelope, printed kraft envelope, plastic windowed printed kraftenvelope, white ledger, manifold white ledger, laser printed whiteledger, colored ledger, manifold colored ledger, super ledger, carboninterleafed ledger, carbonless thermal ledger paper, hard white, mixedtab cards, manila tab cards, colored tab cards, manila file folderstock, soft white, ground wood fiber, magazines, magazines with hotmelt, books, book stock, waxed cup stock, glassine, aseptic packaging,solid fiber containers, or any combination thereof. Starch can bepresent in recycled papers, such as broke, recycled packaging, oldcorrugated containers (OCC), mixed office waste (MOW), coated finepapers or other printing papers, or other indicated recycled papers, andin general all recycled cellulosic materials containing starch. The pulpcan contain at least about 1.0 wt % post-consumer content, at leastabout 10 wt % post-consumer content, at least about 25 wt %post-consumer content, at least about 50 wt % post-consumer content, atleast about 60 wt % post-consumer content, at least about 75 wt %post-consumer content, at least about 90 wt % post-consumer content, atleast about 95 wt % post-consumer content, at least about 99 wt %post-consumer content, or 100 wt % post-consumer content based on thetotal weight of dried pulp.

The pulp source and/or pulp can contain any desired amount of starch.For example, the pulp source and/or pulp can contain starch in an amountof at least 0.1 kg/Tonne (1 Tonne, is a metric tonne=2200 lbs.), atleast about 0.5 kg/tonne, at least about 1 kg/tonne, at least about 5kg/tonne, at least about 10 kg/tonne, at least about 15 kg/tonne, atleast about 20 kg/tonne, at least about 40 kg/tonne, at least about 45kg/tonne, at least about 50 kg/tonne, at least about 75 kg/tonne, atleast about 100 kg/tonne, at least about 250 kg/tonne, greater thanabout 500 kg/tonne, or a range including one or more of such amounts.The starch can be present in the pulp at a desired amount based on thetotal weight of dried pulp fiber. For example, the starch can be presentin the pulp in an amount of at least about 0.001 wt %, at least about0.01 wt %, at least about 0.05 wt %, at least about 0.10 wt %, at leastabout 0.50 wt %, at least about 1.0 wt %, at least about 5.0 wt %, atleast about 10 wt %, at least about 15 wt %, at least about 25 wt %, atleast about 50 wt % based on the total weight of dried pulp fiber, or arange including one or more of such amounts. For example, the starchcontent can be at least about 10 wt % including from about 2.0 wt % toabout 3.0% wet end cationic starch, from about 2.0 wt % to about 5.0 wt% size double sided stock, and from about 1.0% to about 4.0% starch fromglue based on the total weight of dried pulp fiber. The starch that ispresent in the pulp and/or process water can be a result of the starchpresent in the pulp (such as starch that is from recycled sources suchas packaging and/or paperboard) and/or can be a result of additionalstarch added to the pulp and/or process water.

Starch can be measured, before, after, and/or during treatment of thepulp using any suitable or desired method. Starch molecular weight (MW)distribution can be measured, for example, through size exclusionchromatography. The methods of the present invention can enable anincreased quantity and average molecular weight of starch recovered fromrecycled fiber as well as broke in the context of virgin fiber packagingmills. Increased MW of starch helps achieve improved mechanicalproperties. The average MW in Daltons of amylose, amylopectin, and/ortotal starch in the pulp can be at least 1.0×10³ D, at least 1.0×10⁴ D,at least 1.0×10⁵ D, at least 5.0×10⁵ D, at least 1.0×10⁶ D, at least2.5×10⁶ D, at least 5.0×10⁶ D, at least 7.5×10⁶ D, or at least1.0×1.0×10⁷ D.

The starch can be endogenous and/or exogenous to the pulp source and/orpulp. The pulp can be supplemented with additional starch at any desiredtime point, location, or rate. The starch can be obtained from anysource or combination of sources. Any kind of starch or combination ofstarches can be used. The starch can have any desirable amounts and/orrelative amounts of amylose and amylopectin. For example, the starch cancontain from about 5.0 wt % to about 50 wt % amylose and from about 50wt % to about 95 wt % amylopectin, from about 10 wt % to about 35 wt %amylose and from about 65 wt % to about 90 wt % amylopectin, or fromabout 20 wt % to about 25 wt % amylose and from about 75 wt % to about80 wt % amylopectin based on the total weight of the starch. The starchcan contain cationic starch, anionic starch, or a combination thereof.The starch can be modified, unmodified, or a combination thereof.Modified starch can include, for example, one or more of hydroxyethylstarch, carboxymethylated starch, dextrin, acid-treated starch,alkaline-treated starch, bleached starch, oxidized starch,enzyme-treated starch, monostarch phosphate, distarch phosphate,phosphated distarch phosphate, acetylated distarch phosphate, starchacetate, acetylated distarch adipate, hydroxypropyl starch,hydroxypropyl distarch phosphate, hydroxypropyl distarch glycerol,starch sodium octenyl succinate, an acetylated oxidized starch, or anycombinations thereof.

With the present invention, the process water containing the pulp hasvery low amylolytic bacteria counts and/or other bacteria. Theamylolytic bacteria can be present at less than about 0.1 colony formingunits (cfu) per gram of pulp dry weight (d.w.), less than about 10 cfu/gpulp d.w., less than about 1,000 cfu/g pulp d.w., less than about1.0×10⁵ cfu/g pulp d.w., less than about 1.0×10⁶ cfu/g pulp d.w., lessthan about 1.0×10⁸ cfu/g pulp d.w., less than about 1.0×10¹⁰ cfu/g pulpd.w., less than about 1.0×10¹² cfu/g pulp d.w., less than about 1.0×10¹⁵cfu/g pulp d.w. Essentially, with the present invention, the amylolyticbacteria are controlled such that the bacteria cause no significantbreakdown of the starch in the pulp. For instance, with the presentinvention, the amount of starch originally present (when added to theprocess water) is not reduced by more than 50% by weight once in thepaper made from the pulp. Put another way, at least 50% by weight of thestarting amount of starch in the starting pulp can make its way into thepaper resulting from the pulp and this can be at least 60 wt %, at least70 wt %, at least 80 wt %, at least 90 wt %, at least 95 wt %, such asfrom 60 wt % to 99 wt %.

The methods of the present invention can involve control or preventionof amylase production and/or activity (such as α-amylase productionand/or activity). Control or prevention of amylase can be carried outusing any suitable technique or combination of techniques. For example,amylase production can be controlled and/or prevented by killingmicrobes, or other microorganisms, that produce amylase or inhibitingproduction of amylase by microbes. External amylases, such asα-amylases, in recycled paper, broke, or other materials introduced intoa papermaking process or other process, can be inactivated with use ofthe indicated double treatment that includes use of oxidant, such asNaOCl. Amylase (such as α-amylase) that is produced or otherwise presentcan be inhibited and/or degraded. By controlling or preventing, theretention of starch in the pulp and eventually into the resulting paperis achieved, for instance, in the amounts described in the aboveparagraph. The indicated double treatment strategy with chloramine andoxidant (e.g., NaOCl) can provide a paper sheet with greater strength ascompared to a paper sheet made with a similar process that does notinclude the oxidant (e.g., NaOCl) treatment. In an alternative, whenoxidant (e.g., NaOCl) addition is included in the process, less addedstrengthening aid may be needed to provide a similar level of productstrength as compared to paper sheeting made with a similar process thatexcludes the oxidant (e.g., NaOCl) treatment.

Any suitable chloramine or combination of chloramine can be used in themethods of the present invention. The chloramine can containmonochloramine or other chloramine, or any combination thereof. Thechloramine can be obtained from any suitable source. For example,BUSPERSE 2454 product, BUSAN 1215 product, and BUCKMAN 1250 product,available from Buckman Laboratories International, Inc., Memphis, Term.,can be used as precursors (1:1 molar ratio to NaOCl in bleach) to formchloramine. The chloramine can be prepared accordingly to any suitablemethod. For example, chloramine can be produced by one or more techniquedescribed in U.S. Pat. Nos. 4,038,372, 4,789,539, 6,222,071, 7,045,659,and 7,070,751, which are incorporated herein in their entireties. Thechloramine can be formed as a stock solution that can be introduced tothe process water. The chloramine can be formed in-situ in the processwater. The chloramine can be formed by reacting at least one ammoniumsalt with at least one chlorine-containing oxidant. The chloramine canbe formed by reacting at least one ammonium salt with sodiumhypochlorite or calcium hypochlorite or both. For example, the ammoniumsalt can be ammonium bromide, ammonium sulfate, ammonium hydroxide,ammonium chloride, or a combination thereof. Monochloramine can beproduced by reacting 1 to 1 molar ratio of the ammonium salt andchlorine.

Any suitable oxidant or combination of oxidants can be used in theindicated dual treatment methods of the present invention as the oxidantused to reduce or eliminate starch-degrading enzymes, such as amylase.Oxidants can be used in the dual treatment method that are incompatibleor compatible with monochloramine. As indicated, NaOCl is incompatiblewith monochloramine, wherein NaOCl releases free chlorine that reactswith the monochloramine and thus eliminates it. Other oxidants which areincompatible with chloramine which can be used are hypohalite compounds(e.g., OBr⁻), halogen oxidants added through halogen stabilisers such ashalogenated hydantoins (e.g., bromochloro-5,5-dimethylhydantoin orBCDMH), DMH with bleach, urea with bleach, and the like. For example,though NaOCl is illustrated herein, other alkali metal hypohalites oralkaline earth metal hypohalites can be used, including any combinationsthereof. Hypohalite salts may be added to process water in liquid orsolid particulate forms, depending on the specific material. Oxidantswhich are effective to reduce or eliminate starch-degrading enzymes thatare compatible with monochloramine can be used. Compatible oxidants donot release free halogen that reacts with the monochloramine. Theoxidants which can be compatible with monochloramine can be chlorinedioxide (ClO₂), peroxides such as hydrogen peroxide (H₂O₂), peraceticacid (PAA), perfluoric acid (PFA), or others, and in any combinationsthereof.

FIG. 1 shows a method, indicated as process 100 comprising steps101-106, for the treatment of process water that contains pulp withchloramine. The treatment can be performed at one or more stages orlocations in a papermaking system. For example, the treatment can beperformed in a vessel such as a head box. The treating can occur at ahead box, upstream of a head box, downstream of a head box, or anycombination thereof. Multiple addition points per location can beinterchangeable. In a system with a single water loop shared betweenpulper to machine, examples of addition points can include one or moreof the following: pulper(s), pulper fill water, a dump chest, a mixingor machine chest, a head box, and/or white water. In a system with twowater loops defining a stock preparation part and a machine part,examples of addition points can include one or more of the following:stock preparation, pulper(s), pulper fill water, a dump chest, stockchest(s), stock loop process water, a paper machine, a mixing or machinechest, a head box, broke, and white water. Stored broke can receiveadequate treatment. If multiple lines (short/long) are employed,treatment can be maintained in at least one line, in more than one line,or in all lines.

The amount of chloramine and/or precursors used for treating the pulpcan be constant or variable. A target residual chloramine value or rangecan be achieved by the treatment. For example, the process water canhave a residual chloramine amount of from about 0.1 ppm to about 30 ppm,from about 0.3 ppm to about 15 ppm, from about 0.5 ppm to about 12 ppm,from about 1.0 ppm to about 10 ppm, from about 2.0 ppm to about 8.0 ppm,from about 4.0 to about 7.5 ppm, from about 5.0 to about 7.0 ppm in theprocess water containing the pulp. As stated, this amount can beconsidered a chlorine equivalent. This would also be applicable forwhite waters, and/or various filtrates—superclear, clear and cloudy.This residual chloramine amount can be an average chloramine amountbased on a 24-hour period. The level of chloramine to pulp can be atleast about 0.10 lb. chloramine per ton of dry pulp (1 ton=2000 lbs.),at least about 0.30 lb. of chloramine per ton of dry pulp, at leastabout 0.75 lb. of chloramine per ton of dry pulp, at least about 1.0 lb.of chloramine per ton of dry pulp, at least about 1.25 lbs. ofchloramine per ton of dry pulp, at least about 1.6 lbs. of chloramineper ton of dry pulp, at least about 2.0 lbs. of chloramine per ton ofdry pulp, at least about 2.5 lbs. of chloramine per ton of dry pulp, atleast about 3.0 lbs. of chloramine per ton of dry pulp, or at leastabout 5.0 lbs. of chloramine per ton of dry pulp. The level ofchloramine to pulp can be at least about 50 g of chloramine per tonne (1tonne=2200 lbs.) of dry pulp, at least about 150 g of chloramine pertonne of dry pulp, at least about 350 g of chloramine per tonne of drypulp, at least about 500 g of chloramine per tonne of dry pulp, at leastabout 700 g of chloramine per tonne of dry pulp, at least about 800 g ofchloramine per tonne of dry pulp, at least about 1.0 kg of chloramineper tonne of dry pulp, at least about 1.25 kg of chloramine per tonne ofdry pulp, at least about 1.5 kg of chloramine per tonne of dry pulp, atleast about 3.0 kg of chloramine per tonne of dry pulp, or at leastabout 5.0 kg of chloramine per tonne of dry pulp.

The treatment of the pulp with chloramine can be continuous,substantially continuous, intermittent, cyclic, batch, or anycombination thereof. Treatment can be repeated any desired number oftimes and treatments can be separated by constant or variable timeperiods. The addition of chloramine and/or precursors to the pulp can becontinuous, substantially continuous, intermittent, cyclic, batch, orany combination thereof. The rate of addition of chloramine and/orprecursors can be constant or variable. Chloramine, and/or precursorsthereof, can be added in any manner to the process water, for example,by pouring, by nozzle, by spraying, by misting, by curtain, by weir, byfountain, by percolation, by mixing, by injection, or by any combinationthereof. The process water can be treated for any period of time. Forinstance, on a substantially continuous or continuous basis, such as atleast about 6.0 hours, at least about 12 hours, at least about 24 hours,at least about 36 hours, or at least about at least 7 days, at least 2weeks, at least 1 month, at least 2 months, at least 3 months, from 1day to 6 months, from 1 day to 12 months or more. The amount ofchloramine added can be varied based on any one or combination ofdifferent factors, for example, starch concentration, amylaseconcentration, microbial concentration, conductivity, redox potential,turbidity, amount of pulp, cation concentration, anion concentration,calcium ion concentration, volatile fatty acid (VFA) concentration, andpH.

The process water can have a constant or variable pH during thetreatment of the pulp with chloramine. The pH can be at least about 5.0,at least about 6.0, at least about 6.5, at least about 7.0, at leastabout 8.0, at least about 10.0, or at least about 12.0. The processwater can have a constant or variable temperature during the treatmentof the pulp with chloramine. For example, the temperature can be atleast about 5° C., at least about 10° C., at least about 20° C., atleast about 25° C., at least about 30° C., at least about 40° C., atleast about 50° C., at least about 60° C., or at least about 75° C.

In the present invention, the minimizing of calcium ion formation in theprocess water is achieved. This prevents fouling of one or morecomponents of the papermaking process and/or tanks/reactors. Moreimportantly, by minimizing the calcium ion formation, this means thatthe calcium (e.g., calcium carbonate) stays with the pulp and eventuallyis present in the resulting paper product, and further this means thatthe calcium ion concentration in the process water (after pulp removal)is low thus resulting in controlled (or prevention of) calciumprecipitation and/or scaling in the waste water treatment part of theprocess (such as the digesters and/or BOD systems). “Precipitation” canrefer to settling or fall out of solids or insolubility, and “scaling”can refer to a specific process that forms deposits. For example, Ca²⁺ion levels in the process water can be less than about 5000 ppm, lessthan about 2500 ppm, less than about 1200 ppm, less than about 1000 ppm,less than about 800 ppm, less than about 500 ppm, less than about 250ppm, or less than about 100 ppm, such as from 10 ppm to 5000 ppm, from50 ppm to 3,000 ppm, from 100 ppm to 2,000 ppm. This is especially thecase once the pulp is substantially or entirely removed from the processwater and this calcium concentration would be right before entering thewaste water treatment part, such as right before entering the digester(s) or other BOD treatment equipment.

The methods of the present invention can further include formingpackaging sheets/boards. Such packaging sheets/boards can have anydesirable starch content. For example, packaging sheets/boards can havea starch content of at least about 1.0 kg/ton (1 ton=2000 lbs.), atleast about 2.5 kg/ton, at least about 5.0 kg/ton, or at least about10.0 kg/ton of packaging sheets/boards. Strength of packagingsheets/boards and other paper products made using the methods of thepresent invention can be measured using any suitable technique, forexample, the span compression test (SCT), the burst test, and/or thering crush/Concora test. The present invention also provides systemsemploying the methods described herein as well as packaging and otherpaper products produced by the methods described herein. The methodsdescribed herein can be performed in aerobic systems, anaerobic systems,or any combination thereof.

As indicated above, the present invention can relate to a method to usechloramine and sodium hypochlorite in a coordinated manner in the sameprocess. Chloramine (e.g., monochloramine) can provide excellentperformance for cost in high demand systems as a biocide enabling therigorous level of infection control that is required to keep amylaselevels very low. In direct tests, chloramine as an oxidizing agent showsvirtually no activity to inactivate amylases specifically, although itcan be active with respect to other enzymes. NaOCl is an inefficientbiocide in high demand systems, even at very high treatment rate. Indirect tests, NaOCl is very efficient at inactivating amylases (andenzymes in general).

To provide these coordinated effects, chloramines can be added in theindicated dosages herein, and the oxidant (such as NaOCl) used tocontrol starch-degrading enzymes can be added in dosages at from about10 wt % to about 50 wt %, or from about 10 wt % to about 45 wt %, orfrom about 15 wt % to about 50 wt %, or from about 20 wt % to about 40wt %, of the actual chlorine demand in the treated solution. The“chlorine demand” can be the total amount of chlorine which would beused up in reactions with all chlorine-reactable compounds in theprocess solution and without leaving residual chlorine therein. Theindicated dosages herein for the chloramine and oxidant (e.g., NaOCl)can be the amount of the respective active added to the process solutionthat is not reacted with the other indicated double treatment active inthe process solution, and thus available to treat the process solution.The oxidant sodium hypochlorite (NaOCl) can be added in an aqueous form.NaOCl can be used in the methods herein in dilute aqueous forms, such asaqueous forms which can contain up to about 15 wt % chlorine (e.g., fromabout 1 wt % to about 15 wt % NaOCl), or other concentrations.

As shown by experimental results in an example herein, it has beendemonstrated in laboratory tests that the addition of NaOCl at from 10%to 50% of the actual chlorine demand in high demand solutions containingamylases was enough to reduce or eliminate the amylase activity. Asindicated, a double treatment strategy can be provided wherein NaOCl isused to eliminate amylase from the process, and chloramine is used toeliminate infection and prevent amylase production in the process. Thecombination of both treatments in a process results in a much moreefficient treatment wherein a synergy between both treatments isobtained. Chloramine reduces and keeps infection and amylases low, andNaOCl eliminates whatever amylases still exist, such as α-amylases,thereby prevents starch degradation and reduces nutrient availabilityfor the infection. Amylases can come in with poor quality old papers(wet, infected, moulded). Chloramine does not usually have any impact onthe incoming amylases. NaOCl also inactivates external amylases thatcome into the process. Other sources of external amylases could beprocess waters imported from untreated paper machines, reused(partially) treated effluents that replace fresh water. Another sourceof amylases can be recycled fiber stock chests, deinking fiber stockchests or broke chests that have (occasional) very long residence timewhich renders any infection control, also with monochloramine,problematic; NaOCl can be used to eliminate amylase from the stock usedfrom such chests and such prevent further contamination of processwaters with amylases.

FIG. 2 shows a method, indicated as process 200 comprising steps201-210, for the indicated double treatment of process water thatcontains pulp with native starch with chloramine and sodiumhypochlorite. As indicated, in a method of treating process water withchloramine and an incompatible oxidant such as NaOCl or other freehalogen-releasing oxidant, chloramine and free chlorine from NaOCl,and/or other incompatible oxidant, preferably are not present togetherin the process water because the chloramine reacts with the freechlorine resulting in destruction of the two actives. Therefore, bothactives preferably are kept separated (or substantially separated) fromeach other in the process water undergoing processing. This separationof chloramine and NaOCl (or other incompatible oxidant), where used asthe oxidant, in the process water can be achieved in different ways.NaOCl (or other incompatible oxidant) and chloramine can be added atdifferent positions in the process and as both actives are consumed asthey move further through the process this will prevent them frommixing. NaOCl (or other incompatible oxidant) and chloramine can besequentially added from the same position with a time delay betweentheir respective additions. If chloramine is added to the process waterbefore NaOCl (or other incompatible oxidant) addition, the delay of theaddition of the NaOCl (or other incompatible oxidant) can be controlledto allow for the level of previously added chloramine to be below about5 ppm, or below 1 ppm, or below detectable limits. By properlycontrolling chloramine addition upstream from the positions where NaOCl(or other incompatible oxidant) is added, the presence of chloramine atthese positions can be prevented. In recycled fibre systems, typicallyresiduals of chloramine are very low. After the chloramine treatment isstopped, if a chloramine residual is present it quickly disappears.After an appropriate (adjustable) delay after chloramine addition isstopped, NaOCl (or other incompatible oxidant) can be dosed. Asindicated, NaOCl (or other incompatible oxidant) can be added insub-demand concentrations, wherein free chlorine does not move forwardfrom its position of addition before chloramine is added (or re-added).Places for adding the NaOCl (or other incompatible oxidant) in apapermaking process can be the pulper and high density chests, or otherlocations. After the NaOCl (or other incompatible oxidant) dosing isstopped, because a sub-demand treatment can be applied and no residualis present, chloramine dosing can resume, such as resume immediately.The resumed addition of chloramine after NaOCl (or other incompatibleoxidant) addition can be optional, such as depending on the needs of theprocess system being treated. Both spatial and temporal separation ofchloramine and NaOCl have been successfully used in tests done onindustrial systems, whereby no mutual negative impact of the actives wasdetected. Experimental industrial results have shown that betterefficacy of overall treatment can be obtained with lower chloramineaddition rates, a lower overall cost of treatment, better strengthcharacteristics of the new sheet, or combinations of these can beobtained. Experimental industrial results show that the method providesnot only the efficient biocide/chloramine treatment, but it adds aspecific double treatment approach with NaOCl that specifically targetsthe amylase in the process.

As indicated above, the present invention also relates to a method tocontrol or prevent calcium precipitation and/or scaling in an aerobic oranaerobic digester(s) that processes process water used in papermakingand that contained calcium from pulp being process, the methodcomprising in a papermaking process, continuously treating process watercontaining said pulp with chloramine comprising monochloramine such thatsaid process water, when said pulp is present, has a residual chloramineamount, such as from 0.3 ppm to 15 ppm (or the other residual amountsmentioned earlier), wherein calcium is present in said pulp, and thenforming paper/paperboard from said pulp, and processing said processwater, after pulp removal, to one or more digesters.

The present invention also relates to a method to control or preventcalcium precipitation and/or scaling in a biological oxygen demandreduction (BOD) system that processes process water used in papermakingand that contained calcium from pulp being processed, said methodcomprising in a papermaking process, continuously treating process watercontaining said pulp with chloramine comprising monochloramine such thatsaid process water, when said pulp is present, has a residual chloramineamount of from 0.3 ppm to 15 ppm (or the other residual amountsmentioned earlier), wherein calcium is present in said pulp, and thenforming paper/paperboard from said pulp, and processing said processwater, after pulp removal, to said BOD system to reduce BODs.

In the methods above, involving the digesters and/or BOD systems, thecalcium ion amount present in the process water after pulp removal canbe 5000 ppm or less, 2000 ppm or less, 1000 ppm or less, 500 ppm orless, or from about 10 ppm to 500 ppm (based on the process water thatreaches the digester or BOD system equipment).

In addition or in the alternative, the chemical oxygen demand (COD) canbe measured and controlled by the present invention. The COD is a fastertest method to determine or predict what the BOD is for the system. BODtesting can take days whereas COD testing can be minutes to hours todetermine. One COD test procedure that can be used is the test describedin Standard Methods—For the Examination of Water and Wastewater, 17^(th)Ed., Am. Public Health Assoc. et al, pp. 5-12, where the Chemical OxygenDemand (5220B)/Open Reflux Method. Thus with the present invention, CODdemand can be controlled or reduced using the methods of the presentinvention. Essentially the nutrients that bacteria can feed on, likestarch or the breakdown of starch can be reduced using the methods ofthe present invention, since the starch is retained in the pulp andeventually in the paper using the processes of the present invention.

The residual chloramine concentration of the process water, whenentering the digester or BOD system equipment can be much lower, such asbelow 0.3 ppm (e.g., 0.00001 ppm or less, 0 ppm, 0.01 ppm or less, 0.1ppm or less, 0.001 ppm or less) and the like.

With the present invention, the starting starch levels found in the pulpwith process water (at the start of the papermaking process) compared tothe starch levels in the pulp and process water (right before theseparation of the pulp from the process water—e.g., right before thepulp is placed on the screen) is within 50% by weight, within 40% byweight, within 30% by weight, within 20% by weight, within 10% byweight, within 5% by weight, or within 1% by weight. In other words,with the present invention, the starch levels are preserved through theprocess and are not degraded or broken down by bacteria.

With the present invention, the difference between the ppm levels of thestarting calcium levels (e.g. dissolved calcium, Ca²⁺) found in the pulpwith process water (at the start of the papermaking process) compared tothe calcium levels of the process water after the pulp is removed is atmost an increase of 500 ppm (+500 ppm or less), such as at most anincrease of 250 ppm (+250 ppm or less), at most an increase of 100 ppm(+100 ppm or less), at most an increase of 50 ppm (+50 ppm or less), andmore preferably, a decrease in the calcium levels, such as a decrease ofat least 50 ppm (−50 ppm or more), a decrease of at least 100 ppm (−100ppm or more), a decrease of at least 250 ppm (−250 ppm or more), adecrease of at least 500 ppm (−500 ppm or more), a decrease of at least1000 ppm (−1000 ppm or more), a decrease of at least 2000 ppm (−2000 ppmor more), a decrease of at least 3000 ppm (−3000 ppm or more), withrespect to starting versus final calcium levels in the process water asdescribed above.

The following examples are given to illustrate the nature of theinvention. It should be understood, however, that the present inventionis not to be limited to the specific conditions or details set forth inthese examples. Unless stated otherwise, in the Examples, the referenceto “tonne” is a metric tonne and is based on “per tonne” of dry pulp.

EXAMPLES Example 1

This example demonstrates one or more of the superior benefits of thepresent invention. A new anaerobic digester was being used at aneffluent plant that received waste water from papermaking (after pulpremoval). Prior to the present invention, the plant reported loss ofperformance of the anaerobic digester from calcium precipitation and/orscaling and also reported blocking of the digester from precipitationand/or scaling. The plant had to shut down the digester to clean thedigester (scale removal) This resulted in significant down time for theplant and unscheduled expenses to clean the digester. The plantoperators did not understand the cause of the problem or a solution. Thepresent inventor offered an experimental trial to see if the presentinvention would work in the field. The process water that became thewaste water that entered the digester was treated. In particular, theprocess water (which contained pulp) was treated with chloroamines(primarily monochloramine) in an amount of 300 g/tonne at the pulpers ofthe papermill and also at the top ply whitewater (WW) silo. This wasdone on a continuous basis. The amount of calcium ion concentration(dissolved in water) in the process water at the start of the pulpprocess (before the headbox) was measured and also the amount of calciumconcentration right before entering the digester was measured and thedifference in calcium was determined. Prior to using the presentinvention, the calcium ion concentration increased 2000 ppm. This was avery negative, undesired occurrence. Once the present invention's methodwas used for 2 to 3 days (continuously), the difference in calciumconcentration was determined again, and the change in calciumconcentration had eventually gone to a minus 2,500 ppm. In other words,the amount of dissolved calcium at the digester was lowered by over2,500 ppm compared to the amount of calcium at the start of the pulpingat the papermill. This was an incredible turn around, which preventedthe fouling of the digesters. Also, due to reducing the calcium content,the resulting sludge can be considered anaerobic sludge and not chemicaldisposal.

Further, in the pulp mill where the process water (waste water) camefrom, the pulp was recycled pulp (including recycled packaging) and hada high starch content. Prior to the use of the present invention, asdescribed above, the initial starch content at the time of mixing withwater went down significantly during the processing of the pulp, suchthat the wet sheets formed from the pulp had a significantly reducedstarch content. It was discovered, by the present inventor, that thestarch was being broke down by amylolytic bacteria. By using the methodsof the present invention, besides achieving control of the calciumprecipitation and/or scaling, the present invention also controlled theconsumption of starch by controlling the bacteria. As a result,significant levels of the starting amount of starch were preserved andincorporated into the paper formed from the pulp.

Example 2

This example also demonstrates one or more of the superior benefits ofthe present invention. An anaerobic digester was being used at differenteffluent plant that received waste water from papermaking (after pulpremoval). Prior to the present invention, the plant reported loss ofperformance of the anaerobic digester from calcium precipitation and/orscaling and also reported blocking of the digester from precipitationand/or scaling. The plant had to shut down the digester to clean thedigester (scale removal). This resulted in significant down time for theplant and unscheduled expenses to clean the digester. The plantoperators did not understand the cause of the problem or a solution. Thepresent inventor offered an experimental trial to see if the presentinvention would work in the field. The process water that became thewaste water that entered the digester was treated. In particular, theprocess water (which contained pulp) was treated with chloroamines(primarily monochloramine) in an amount of 300 g/tonne to 600 g/tonne atthe pulper dilution water of the papermill and also at the thickstock-before fractionation in an amount of 400 to 800 g/tonne, and atthe whitewater (WW) flume in an amount of 400 to 800 g/tonne. This wasdone on a continuous basis. The amount of calcium ion concentration(dissolved in water) in the process water at the start of the pulpprocess (before the headbox) was measured and also the amount of calciumconcentration right before entering the digester was measured and thedifference in calcium was determined. Prior to using the presentinvention, the calcium ion concentration increased 4000 ppm. This was avery negative, undesired occurrence. Once the present invention's methodwas used for 2 to 3 days (continuously), the difference in calciumconcentration was determined again, and the change in calciumconcentration had eventually gone to a minus 700 ppm. In other words,the amount of calcium at the digester was lowered by over 500 ppmcompared to the amount of calcium at the start of the pulping at thepapermill. This was an incredible turn around, which prevented thefouling of the digesters. Also, due to reducing the calcium content, theresulting sludge can be considered anaerobic sludge and not chemicaldisposal.

Example 3

Experimental tests were conducted to evaluate the effects of addingNaOCl to high demand solutions containing amylases, includingα-amylases.

In the experiments described below, amylase activity was measured usinga synthetic α-amylase substrate, “RED-STARCH” obtained from MEGAZYME®(Ireland), and a test procedure developed that allows the use of thissubstrate in complex paper mill process waters including samplescontaining cellulose.

The indicated test procedure developed for testing paper mill samplesfor α-amylase activity includes preparation of the substrate by adding 1g of powdered RED-STARCH substrate to 50 mL of 0.5 M KCl solution (7.45g/100 ml), and warming up to 60° C. whilst shaking vigorously untildissolved. The prepared substrate can be used fresh or stored underrefrigeration until used. A concentrated assay buffer solution wasprepared as a 300 mM CaCl₂.2H₂O solution (39.2 g/l), which for use, isdiluted 200 times in the assay. Assays can be performed on any liquidsample recovered in a paper mill. Samples with high turbidity mayinterfere with the final measurement step. Accordingly, samplescontaining fiber can be filtered through a paper filter, and liquid fromhigh consistency samples can be recovered by squeezing liquid from thesample. To perform the assay on a sample, 30 μl assay buffer, 3 mlRED-STARCH substrate solution, and a 3 ml test sample solution can beadded to a 35 ml test vial, and mix and incubate the vial and contentsat constant temperature (35-40° C.) for 30 minutes. The reaction isended by adding 10 ml ethanol (denatured) or methanol and shakingvigorously, and then allowing the vial and its contents to stand for 2minutes before filtering the contents through a paper filter. Highmolecular weight material can be removed by the filtering. Using a 10 mlsyringe, the filtered liquid is passed through a 0.22 or 0.45 μmdisposable filter cartridge. The liquid that passes through thecartridge is introduced into a spectrophotometer cuvette, and theabsorbance (OD) of the reaction solution, and a separate reaction blank,are measured using a spectrophotometer. The reaction blank is preparedby adding 10 ml ethanol or methanol to a test vial first, then add 30 μlassay buffer, 3 ml red starch substrate solution, and a 3 ml testsolution, and prepare the samples for measurement as above. Thespectrophotometer can be a Hach DR/890 Colorimeter (Hach Company,Loveland Colo.), or other spectrophotometer device. Absorbance can bemeasured as optical density (OD). On incubation of the RED-STARCHsubstrate with α-amylase, the substrate can be depolymerized to producelow molecular weight dyed fragments which remain in solution on additionof alcohol to the reaction mixture. The measured value of OD is directlyproportional to the α-amylase activity in the test sample. Mostspectrophotometers have a scale that reads in OD (absorbance) units,which is a logarithmic scale. A user edited program can be entered intothe DR/890 device, including choosing a wavelength of 510 nm at whichabsorbance is measured, using water as a blank (OD=0), and preparing amaximum α-amylase activity sample by adding a small amount of BUZYME®2508 (Buckman Laboratories, Belgium) to water and using this in theassay (max. OD that can be measured is approximately 25). The range thatis obtained with this program is very large and can suffice for allpaper mill samples. Using this testing procedure, paper mill samplestypically have absorbance values in the range of 1-7. If a sample givesa maximum reading, it can be diluted in water to determine a moreprecise value. Results can be represented as the actual number or as apercentage of the maximum reading of the procedure which is 25. Theresults in Table 1 below show results for α-amylase activity as apercentage of the maximum reading.

In the tests conducted, process water was used that was taken from acoated paper machine pulper fill water tank that was not being treatedwith an oxidizing program. First, the actual chlorine and monochloramine(NH₂Cl) demands of this process water were determined (Table 1). To thisprocess water, a commercial α-amylase was added (BUZYME® 2508, at a1/1000 mixture ratio. From this mix, 30 ml samples were prepared towhich were added sub-demand quantities of NaOCl and monochloramine asshown in Table 1 below. These samples were allowed to incubate for 15minutes at 40° C. before the α-amylase substrate RED-STARCH and thereaction buffer were added. After a contact time of 30 minutes at 40°C., the reaction was stopped by adding alcohol (denatured ethanol ormethanol) and the remaining relative α-amylase activity in each sampledetermined as described in the method above (Table 1).

TABLE 1 Oxidant demand (ppm Chlorine equivalent added) NaOCl NH₂Cl 58 13NaOCl α-amylase NH₂Cl α-amylase (as % of demand) activity (as % ofdemand) activity  0.0% 100.0% 0.0% 100.0% 10.0% 99.2% 10.0% 100.0% 25.0%87.4% 25.0% 98.5% 50/0% 43.8% 50.0% 99.3% 100.0%  2.1% 100.0% 99.1%

The experimental results show that adding NaOCl at between 10% to 50% ofthe actual chlorine demand to a high demand solution containingα-amylase was effective to reduce the α-amylase activity. Addingmonochloramine to the same samples had no significant effect on theα-amylase activity.

Example 4

This example demonstrates experimental tests used to investigate thepresence of starch tightly linked to cellulose fibers in pulp. Anexperimental test for starch quantification in solution based onchemical oxygen demand (COD) measurement was used. Quantifying starch istypically done using iodine. The problem with this method is that itonly works on intact, high molecular weight starch in the correctconfiguration. Starch molecules in varying degrees of degradation tolower molecular weight starch, sugar oligomers or individual sugars arenot detected or measured with iodine. To overcome this problem and havea more robust method to quantify starch and degradation products,chemical oxygen demand (COD) measurements can be used. Especially whenstarch is known to be the only or main COD contributing molecule insolutions, this method can give very accurate and reproducible numbersthat are not affected by the degree to which starch is degraded.

In pulp samples, for example, it was important to be able to determinewhether starch was present in pulp samples tightly linked to thecellulose fibers. To determine this, fiber samples were prepared in thelab or industrial fiber samples were analyzed on site. The pulp wasrecovered for the different suspensions by filtration over a screen,using both 400 micron screens and paper filters as available, andre-suspended in tap water. The pulp was filtered a second time and againre-suspended in tap water. Samples of the pulp prepared like this weresubjected to α-amylase activity and after an adequate incubation timeagain filtered. Also, controls, which were not treated with enzyme, werefiltered again. Finally, the COD in these two (2) final (tertiary)filtrates and in the primary filtrate was determined as a measure forthe starch bound to the cellulose fibers.

For laboratory samples prepared from cardboard boxes (1% fiberconsistency), the following experimental results were obtained:

unwashed pulp producing the primary filtrate upon filtration, withoutα-amylase: COD of the primary filtrate >500 ppm. This COD is the organicmaterial released into solution after pulping of cardboard boxes. Muchof this COD consists of starch and its various degradation products aswell as other organic material not tightly bound to the cellulosefibers;

tertiary filtrate of fiber resuspended in water not containing anyα-amylases, before the last filtration the fiber was left in suspensionfor 1 hour at 40° C. before filtration: COD of the tertiary filtrate <70ppm. After 2 washing cycles, almost no more COD is released mechanicallyfrom the cellulose fiber material that is retained on the filters;

tertiary filtrate of fiber resuspended in water, during the last cycleα-amylase was added to the suspension and a contact time of 1 hour at40° C. was given before filtration: COD of the tertiary filtrate >500ppm, Adding α-amylase to the last fiber suspension releases asignificant amount of organic material from the cellulose fiber that isnot removed through simple mechanical means. Based on the specificity ofamylase for starch as a substrate it is logical to assume that he CODthat was released from the fiber was starch.

In the final test the actual COD measurement was corrected for the CODthat was added with the enzyme addition to give the actual COD releasedfrom the fiber suspension.

The actual amount of COD released after amylase activity into thetertiary filtrate was similar to the amount of COD release from theprimary fiber suspension. Based on this observation it is possible tostate that up to 50% or more of the total starch in recycled board pulpcan be present in complexes with cellulose fibers that are not disruptedthrough simple mechanical actions such as repulping.

From these experimental testing results, it is clear that from the totalCOD/starch present in cardboard box that a significant percentage istightly linked as starch to the fiber. Protecting it from amylasedegradation keeps it tightly associated with fibers, such as by theindicated double treatment method using NaOCl and chloramine, and allowsits efficient transfer into a new sheet manufactured with recycled pulpfrom the cardboard box. On the material tested and the experimentalconditions used, this would correspond to almost 50% of the starch inthe box to move with the fiber.

Example 5

An industrial trial was conducted at a commercial paper mill toinvestigate the efficacy of a double treatment method using chloramineand NaOCl on pulp in the production of different grades of paper. Duringthe trial, size press starch usage for a sheet produced from pulp thathad been subjected to the indicated double treatment before sheetformation was adjusted such that strength is maintained approximatelythe same as that obtained for the sheet made from pulp that does notreceive the double treatment. To do this, the size press starch usageduring the trial was compared to similar product produced outside of thetrial period. Also, other variables such as filler evolution (CaCO₃)were monitored during the trial. Any increase in filler would normallyalso be expected to result in a drop in strength characteristics. Duringthe trial, it was seen from the results that starch usage in the sizepress can be noticeably reduced in the production of different grades ofpaper while maintaining approximately the same paper strength as sheetsproduced without the double treatment. Further, a significant increasein filler retention was seen for sheets produced from pulp that hadreceived the double treatment, while at the same time the strength wasmaintained or slightly increased, and even though the starch usage wasreduced in the size press.

The present invention includes the followingaspects/embodiments/features in any order and/or in any combination:

1. A method to preserve starch present in pulp comprising:

in a papermaking process having a head box, treating process watercontaining said pulp with chloramine comprising monochloramine such thatsaid process water has a residual chloramine amount of from 0.3 ppm to15 ppm at the head box, wherein starch is present in said pulp in anamount of at least 0.001 wt % based on weight of dried pulp fiber.

2. The method of any preceding or following embodiment/feature/aspect,comprising continuously treating the process water containing said pulpwith said chloramine.3. The method of any preceding or following embodiment/feature/aspect,having a roundformer in place of the headbox.4. The method of any preceding or following embodiment/feature/aspect,wherein said pulp is from recycled packaging, old corrugated containers(OCC), mixed office waste (MOW), coated fine papers, or any combinationsthereof.5. The method of any preceding or following embodiment/feature/aspect,wherein said pulp is from recycled packaging, old corrugated containers(OCC), mixed office waste (MOW), and/or coated fine paper that containsat least 20 kg/tonne of starch.6. The method of any preceding or following embodiment/feature/aspect,further comprising forming packaging sheets/boards having a starchcontent of at least 5 kg/tonne of packaging sheets/boards.7. The method of any preceding or following embodiment/feature/aspect,wherein production of amylase, such as α-amylase, is controlled orprevented.8. The method of any preceding or following embodiment/feature/aspect,wherein amylolytic bacteria are present in an amount of less than about1.0×10¹⁵ cfu/g dry pulp in said process water.9. The method of any preceding or following embodiment/feature/aspect,wherein amylolytic bacteria are present in an amount of less than about1.0×10¹⁰ cfu/g pulp d.w. in said process water.10. The method of any preceding or following embodiment/feature/aspect,wherein amylolytic bacteria are present in an amount of less than about1.0×10⁵ cfu/g pulp d.w. in said process water.11. The method of any preceding or following embodiment/feature/aspect,wherein said continuously treating comprises at least 12 hours.12. The method of any preceding or following embodiment/feature/aspect,wherein said continuously treating comprises at least 24 hours.13. The method of any preceding or following embodiment/feature/aspect,wherein said continuously treating comprises at least 36 hours.14. The method of any preceding or following embodiment/feature/aspect,wherein said continuously treating comprises at least 7 days.15. The method of any preceding or following embodiment/feature/aspect,wherein Ca²⁺ ion levels in said process water are less than 1200 ppm.16. The method of any preceding or following embodiment/feature/aspect,wherein Ca²⁺ ion levels in said process water are less than 1000 ppm.17. The method of any preceding or following embodiment/feature/aspect,wherein Ca²⁺ ion levels in said process water are less than 800 ppm.18. The method of any preceding or following embodiment/feature/aspect,wherein said treating occurs at the head box or upstream of said headbox.19. The method of any preceding or following embodiment/feature/aspect,wherein said chloramine is formed as a stock solution that is introducedto said process water.20. The method of any preceding or following embodiment/feature/aspect,wherein said chloramine is formed in-situ in said process water.21. The method of any preceding or following embodiment/feature/aspect,wherein said chloramine is formed by reacting at least one ammonium saltwith at one chlorine containing oxidant.22. The method of any preceding or following embodiment/feature/aspect,wherein said chloramine is formed by reacting at least one ammonium saltwith sodium hypochlorite or calcium hypochlorite or both.23. Packaging sheets/boards produced using the method of any precedingor following embodiment/feature/aspect.24. A method for microorganism control and starch protection in pulp ina papermaking process comprising a dual treatment of process watercontaining pulp with biocide and oxidant, wherein the biocide reducesmicroorganisms capable of producing starch-degrading enzymes, and theoxidant reduces enzymatic activity of starch-degrading enzymes on starchcontent of the pulp.25. A method to preserve native starch present in pulp comprising:

in a papermaking process, treating process water containing pulpcomprising complexes or aggregates of cellulose and native starch,wherein said treating comprises separately adding chloramine and oxidantto said process water, wherein starch-degrading enzyme content in thetreated process water is reduced compared to treatment of the processwater without the oxidant.

26. The method of any preceding or following embodiment/feature/aspect,wherein the starch-degrading enzyme content is amylase content, such asα-amylase content.27. The method of any preceding or following embodiment/feature/aspect,wherein the oxidant is sodium hypochlorite.28. The method of any preceding or following embodiment/feature/aspect,wherein said pulp is from recycled packaging, old corrugated containers(OCC), or broke.29. The method of any preceding or following embodiment/feature/aspect,wherein production of amylase, such as α-amylase, is prevented.30. The method of any preceding or following embodiment/feature/aspect,wherein said adding of said sodium hypochlorite or other oxidantcomprises adding said sodium hypochlorite or other oxidant at from about10% to about 50% of actual chlorine demand of said process water.31. The method of any preceding or following embodiment/feature/aspect,wherein said separately adding said chloramine and said sodiumhypochlorite or other oxidant to said process water comprises addingsaid chloramine to said process water, and after a delay, then addingsaid sodium hypochlorite or other oxidant to said process water.32. The method of any preceding or following embodiment/feature/aspect,wherein said adding of said sodium hypochlorite or other oxidant occursat the pulper or high density chest.33. Packaging sheets/boards produced using the method of any precedingor following embodiment/feature/aspect.34. A method to control or prevent calcium precipitation and/or scalingin an aerobic or anaerobic digester that processes process water used inpapermaking and that contained calcium from pulp being process, saidmethod comprising in a papermaking process, continuously treatingprocess water containing said pulp with chloramine comprisingmonochloramine such that said process water when said pulp is presenthas a residual chloramine amount of from 0.3 ppm to 15 ppm, whereincalcium is present in said pulp, and then forming paper/paperboard fromsaid pulp, and processing said process water, after pulp removal, to oneor more digesters.35. A method to control or prevent calcium precipitation and/or scalingin a biological oxygen demand reduction (BOD) system that processesprocess water used in papermaking and that contained calcium from pulpbeing processed, said method comprising in a papermaking process,continuously treating process water containing said pulp with chloraminecomprising monochloramine such that said process water when said pulp ispresent has a residual chloramine amount of from 0.3 ppm to 15 ppm,wherein calcium is present in said pulp, and then formingpaper/paperboard from said pulp, and processing said process water,after pulp removal, to said BOD system to reduce BODs.36. The method of any preceding or following embodiment/feature/aspect,wherein said calcium ion present in the process water after pulp removalis present in an amount of 5000 ppm or less.37. The method of any preceding or following embodiment/feature/aspect,wherein said calcium ion present in the process water after pulp removalis present in an amount of 2000 ppm or less.38. The method of any preceding or following embodiment/feature/aspect,wherein said calcium ion present in the process water after pulp removalis present in an amount of 1000 ppm or less.39. The method of any preceding or following embodiment/feature/aspect,wherein said calcium ion present in the process water after pulp removalis present in an amount of 500 ppm or less.40. The method of any preceding or following embodiment/feature/aspect,wherein said calcium ion present in the process water after pulp removalis present in an amount of from about 10 ppm to 500 ppm.

The present invention can include any combination of these variousfeatures or embodiments above and/or below as set forth in sentencesand/or paragraphs. Any combination of disclosed features herein isconsidered part of the present invention and no limitation is intendedwith respect to combinable features.

Applicants specifically incorporate the entire contents of all citedreferences in this disclosure. Further, when an amount, concentration,or other value or parameter is given as either a range, preferred range,or a list of upper preferable values and lower preferable values, thisis to be understood as specifically disclosing all ranges formed fromany pair of any upper range limit or preferred value and any lower rangelimit or preferred value, regardless of whether ranges are separatelydisclosed. Where a range of numerical values is recited herein, unlessotherwise stated, the range is intended to include the endpointsthereof, and all integers and fractions within the range. It is notintended that the scope of the invention be limited to the specificvalues recited when defining a range.

Other embodiments of the present invention will be apparent to thoseskilled in the art from consideration of the present specification andpractice of the present invention disclosed herein. It is intended thatthe present specification and examples be considered as exemplary onlywith a true scope and spirit of the invention being indicated by thefollowing claims and equivalents thereof.

What is claimed is:
 1. A method to preserve starch present in pulp comprising: in a papermaking process having a head box, treating process water containing said pulp with chloramine comprising monochloramine such that said process water has a residual chloramine amount of from 0.3 ppm to 15 ppm at the head box, wherein starch is present in said pulp in an amount of at least 0.001 wt % based on weight of dried pulp fiber.
 2. The method of claim 1, comprising continuously treating the process water containing said pulp with said chloramine.
 3. The method of claim 1, having a roundformer in place of the headbox.
 4. The method of claim 1, wherein said pulp is from recycled packaging, old corrugated containers (OCC), mixed office waste (MOW), coated fine papers, or any combinations thereof.
 5. The method of claim 1, wherein said pulp is from recycled packaging, old corrugated containers (OCC), mixed office waste (MOW), and/or coated fine paper that contains at least 20 kg/tonne of starch.
 6. The method of claim 1, further comprising forming packaging sheets/boards having a starch content of at least 5 kg/tonne of packaging sheets/boards.
 7. The method of claim 1, wherein production of amylase is controlled or prevented.
 8. The method of claim 1, wherein amylolytic bacteria are present in an amount of less than about 1.0×10¹⁵ cfu/g dry pulp in said process water.
 9. The method of claim 1, wherein amylolytic bacteria are present in an amount of less than about 1.0×10¹⁰ cfu/g pulp d.w. in said process water.
 10. The method of claim 1, wherein amylolytic bacteria are present in an amount of less than about 1.0×10⁵ cfu/g pulp d.w. in said process water.
 11. The method of claim 1, wherein said continuously treating comprises at least 12 hours.
 12. The method of claim 1, wherein said continuously treating comprises at least 24 hours.
 13. The method of claim 1, wherein said continuously treating comprises at least 36 hours.
 14. The method of claim 1, wherein said continuously treating comprises at least 7 days.
 15. The method of claim 1, wherein Ca²⁺ ion levels in said process water are less than 1200 ppm.
 16. The method of claim 1, wherein Ca²⁺ ion levels in said process water are less than 1000 ppm.
 17. The method of claim 1, wherein Ca²⁺ ion levels in said process water are less than 800 ppm.
 18. The method of claim 1, wherein said treating occurs at the head box or upstream of said head box.
 19. The method of claim 1, wherein said chloramine is formed as a stock solution that is introduced to said process water.
 20. The method of claim 1, wherein said chloramine is formed in-situ in said process water.
 21. The method of claim 1, wherein said chloramine is formed by reacting at least one ammonium salt with at one chlorine containing oxidant.
 22. The method of claim 1, wherein said chloramine is formed by reacting at least one ammonium salt with sodium hypochlorite or calcium hypochlorite or both.
 23. Packaging sheets/boards produced using the method of claim
 1. 24. A method for microorganism control and starch protection in pulp in a papermaking process comprising a dual treatment of process water containing pulp with biocide and oxidant, wherein the biocide reduces microorganisms capable of producing starch-degrading enzymes, and the oxidant reduces enzymatic activity of starch-degrading enzymes on starch content of the pulp.
 25. A method to preserve native starch present in pulp comprising: in a papermaking process, treating process water containing pulp comprising complexes or aggregates of cellulose and native starch, wherein said treating comprises separately adding chloramine and oxidant to said process water, wherein starch-degrading enzyme content in the treated process water is reduced compared to treatment of the process water without the oxidant.
 26. The method of claim 25, wherein the starch-degrading enzyme content is amylase content.
 27. The method of claim 25, wherein the oxidant is sodium hypochlorite.
 28. The method of claim 25, wherein said pulp is from recycled packaging, old corrugated containers (OCC), or broke.
 29. The method of claim 25, wherein production of amylase is prevented.
 30. The method of claim 27, wherein said adding of said sodium hypochlorite comprises adding said sodium hypochlorite at from about 10% to about 50% of actual chlorine demand of said process water.
 31. The method of claim 27, wherein said separately adding said chloramine and said sodium hypochlorite to said process water comprises adding said chloramine to said process water, and after a delay, then adding said sodium hypochlorite to said process water.
 32. The method of claim 27, wherein said adding of said sodium hypochlorite occurs at a pulper or a high density chest.
 33. Packaging sheets/boards produced using the method of claim
 25. 34. A method to control or prevent calcium precipitation and/or scaling in an aerobic or anaerobic digester that processes process water used in papermaking and that contained calcium from pulp being process, said method comprising in a papermaking process, continuously treating process water containing said pulp with chloramine comprising monochloramine such that said process water when said pulp is present has a residual chloramine amount of from 0.3 ppm to 15 ppm, wherein calcium is present in said pulp, and then forming paper/paperboard from said pulp, and processing said process water, after pulp removal, to one or more digesters.
 35. A method to control or prevent calcium precipitation and/or scaling in a biological oxygen demand reduction (BOD) system that processes process water used in papermaking and that contained calcium from pulp being process, said method comprising in a papermaking process, continuously treating process water containing said pulp with chloramine comprising monochloramine such that said process water when said pulp is present has a residual chloramine amount of from 0.3 ppm to 15 ppm, wherein calcium is present in said pulp, and then forming paper/paperboard from said pulp, and processing said process water, after pulp removal, to said BOD system to reduce BODs.
 36. The method of claim 34, wherein said calcium ion present in the process water after pulp removal is present in an amount of 5000 ppm or less.
 37. The method of claim 34, wherein said calcium ion present in the process water after pulp removal is present in an amount of 2000 ppm or less.
 38. The method of claim 34, wherein said calcium ion present in the process water after pulp removal is present in an amount of 1000 ppm or less.
 39. The method of claim 34, wherein said calcium ion present in the process water after pulp removal is present in an amount of 500 ppm or less.
 40. The method of claim 34, wherein said calcium ion present in the process water after pulp removal is present in an amount of from about 10 ppm to 500 ppm.
 41. The method of claim 35, wherein said calcium ion present in the process water after pulp removal is present in an amount of 5000 ppm or less.
 42. The method of claim 35, wherein said calcium ion present in the process water after pulp removal is present in an amount of 2000 ppm or less.
 43. The method of claim 35, wherein said calcium ion present in the process water after pulp removal is present in an amount of 1000 ppm or less.
 44. The method of claim 35, wherein said calcium ion present in the process water after pulp removal is present in an amount of 500 ppm or less.
 45. The method of claim 35, wherein said calcium ion present in the process water after pulp removal is present in an amount of from about 10 ppm to 500 ppm. 